It means that the expected runtime once on battery is very low. It can also fire for a UPS with smaller battery if it has a very short runtime to begin with. For these smaller batteries you'll want to tweak the default monitor a bit.

The monitor that fires this alert is "Any UPS full capacity is < 30 minutes". Try setting it to one of the lower settings below to throttle it a bit:

It means that the expected runtime once on battery is very low. It can also fire for a UPS with smaller battery if it has a very short runtime to begin with. For these smaller batteries you'll want to tweak the default monitor a bit.

The monitor that fires this alert is "Any UPS full capacity is < 30 minutes". Try setting it to one of the lower settings below to throttle it a bit: